package com.learn.Aqs;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.AbstractQueuedSynchronizer;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;

/**
 * 实现自定义锁
 *
 * @author ln
 * @Description: ${todo}
 * @date 2020/12/26
 */
public class AQSTest {
}


//自定义锁（不可重入锁）
class MyLock implements Lock {

    //    独占锁 同步器类
    class MySync extends AbstractQueuedSynchronizer {
        @Override
        protected boolean tryAcquire(int arg) {
            if (compareAndSetState(0, 1)) {
//                加上了锁，并设置owner为当前线程
                setExclusiveOwnerThread(Thread.currentThread());
                return true;
            }
            return false;
        }

        @Override
        protected boolean tryRelease(int arg) {
            setExclusiveOwnerThread(null);
            setState(0);
            return true;
        }

        @Override //是否持有独占锁
        protected boolean isHeldExclusively() {
            return getState() == 1;
        }

        public Condition newCondtion() {
            return new ConditionObject();
        }
    }

    private MySync sync = new MySync();


    @Override //加锁（不成功会进入等待队列）
    public void lock() {
        sync.acquire(1);
    }

    @Override //加锁，可打断
    public void lockInterruptibly() throws InterruptedException {
        sync.acquireInterruptibly(1);
    }

    @Override //尝试加锁（一次，不成功就放弃）
    public boolean tryLock() {
        return sync.tryAcquire(1);
    }

    @Override //尝试加锁，带超时
    public boolean tryLock(long time, TimeUnit unit) throws InterruptedException {
        return sync.tryAcquireNanos(1, unit.toNanos(time));
    }

    @Override //解锁
    public void unlock() {
        sync.release(1);
    }

    @Override //创建条件变量
    public Condition newCondition() {
        return sync.newCondtion();
    }
}